1. Field of the Invention
This invention relates to solar lighting apparatuses and, more particularly, to a solar lighting apparatus having, within a transparent dome, a rotatively-driven reflection mirror to reflect solar light to be introduced into an inside of a building.
2. Description of the Prior Art
In the building such as a house, direct lighting with solar light is possible only to the room opening on an outside. An aperture such as top lighting or vertical well is provided in a center or north part of the building. Thus, solar light is supplied through the aperture to an inside of the building thus supplying light to the inside.
In the aperture, a solar lighting apparatus is installed which has a reflection mirror to be controlled in inclination angle depending upon a position of the sun. The solar light reflected by the reflection mirror is then introduced into the building.
The solar lighting apparatus has a transparent dome having therein a lighting apparatus having a rotatable reflection mirror to allow tracking a position of the sun. The rotatable reflection mirror has a plurality of reflection plates arranged in a cantilever form at a predetermined interval on a support member structured by rolled members, such as angles. The rotatable reflection mirror has a rotary shaft at its center. The rotatable reflection mirror is coupled, in a state directed upward and cantilever-supported, to a rotary drive shaft (see, e.g. the Specification and Drawings of U.S. Pat. No. 5,999,323).
Meanwhile, separately provided are the motor and drive gear arrangement for driving the rotary drive shaft and its control circuit. These are connected through wiring laid in the transparent dome.
In the meanwhile, the rotatable reflection mirror is in a cantilever structure on the support member, as mentioned above. In order to rigidly support the reflection plates (also in cantilever-supported), there is a need of employing structural members in a sectional form having high strength. This however results in increase of weight.
Furthermore, because no consideration is given to provide balance of weight in the rotary shaft part, bending moment is applied at all times to the rotary shaft. Accordingly, high rotational torque is required in driving the rotatable reflection mirror. This in turn requires a high-output drive motor and an increased-capacity power supply.
Therefore it is a primary object of the present invention to provide a novel solar lighting apparatus.
Another object of the invention is to provide a solar lighting apparatus capable of rotating the reflection mirror by a small-sized drive motor.
The present invention is a solar lighting apparatus, comprising: a dome formed of a transparent material; a support member suspended in the dome; a mirror held fixedly on the support member; and a motor for rotating the support member through a rotary shaft.
In this invention, the mirror is held on the support member suspended in the transparent dome. Because the support member is turned by the motor through the rotary shaft, the mirror is allowed to turn tracking the sun thus obtaining efficient lighting with reflection light. Meanwhile, because the support member holding the mirror is suspended in the dome, bending moment is eliminated to reduce drive torque without changing rotational moment. Accordingly, the suspension of the supporting member in the dome eliminates bending moment, thereby reducing drive torque.
Meanwhile, the support member if preferably structured by connecting light-weighted metal pipes reduces the total weight of the apparatus with the rigidity increased. If the support member is made by a plurality of aluminum pipes connected through detachable joints, it is possible to transport in a compact state of disassembling the aluminum pipes to an installation site.
Furthermore, if the support member and the rotary shaft for rotating the support member are coupled by a universal joint, bending moment is eliminated from a rotary part. Further, rotation drive torque can be reduced in addition to the reduction in weight of the support member. As a result, electric energy for driving the motor is to be saved.
According to the present invention, the drive force required for rotating the mirror is reduced and hence an energy-saving effect is expectable.
The above described objects and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.